1. Field of the Invention
The present invention relates to a hermetic rotary compressor.
2. Description of the Prior Art
Generally, a hermetic rotary compressor compresses a refrigerant which has passed through an evaporator and introduces the compressed refrigerant to a condenser.
As shown in FIG. 1, such compressor has a sealed case 10, an electrically-driven mechanism 20, and a compressing mechanism 60. The electrically-driven mechanism 20 is provided into the case 10, and compressing mechanism 60 rotates so as to compress the refrigerant by means of a driving force generated from the electrically-driven mechanism 20.
A discharge pipe 12 is connected to an upper portion of the sealed case 10, while a suction pipe 16 is connected to a lower portion of the sealed case 10. An accumulator 14 is connected with the suction pipe 16.
The electrically-driven mechanism 20 has a stator 22 and a rotor 24. The stator 22 is fixed to an inner peripheral surface of the case 10. Additionally, the rotor 24 is rotatably installed inside the stator 22 and has a predetermined interval with the stator 22. A rotary shaft 24a is press-fitted into the rotor 24. One end of the rotary shaft 24a projects toward the compressing mechanism 60.
In addition, the compressing mechanism 60 has an eccentric section 28 provided at the rotary shaft 24a, a roller 26 surrounding the eccentric section 28, and a cylinder 30 defining a compression chamber 30a into which the roller 26 is received. As shown in FIGS. 2 and 3, a cutaway section 30b is formed in an inner peripheral surface of the cylinder 30. The cutaway section 30b has a vane 32 for dividing the compression chamber 30a into a suction space B and a compression space A. The cylinder 30 is also formed with a resonance chamber 30c and a suction hole 30d with the vane 32 disposed therebetween. One end of the vane 32 is in linear contact with the outer peripheral surface of the roller 26, while the other end thereof is connected with a spring 34 whose one end is connected with the cutaway section 30b. Additionally, the resonance chamber 30c is formed at the compression space A of the compression chamber 30a, while the suction hole 30d is formed at the suction space B of the compression chamber 30a. Meanwhile, the cylinder 30 is fixed to upper and lower end flanges 36 and 38 disposed respectively at the upper and the lower portions thereof. A discharge port 36a is formed in the upper end flange 36 while communicating with the compression space A so as to permit the refrigerant to be discharged therethrough. Also, a discharge valve 40 is positioned at the upper end flange 36 so as to open/close the discharge port 36a.
Thus, the hermetic rotary compressor constructed as described above compresses the refrigerant into the liquefied high temperature and high pressure refrigerant as explained below. First, as the electrically-driven mechanism 20 operates, the rotor 24 rotates at a high velocity. Accordingly, the roller 26 surrounding the eccentric section 28 of the rotary shaft 24a rotates within the compression chamber 30a of the cylinder 30.
In this situation, the refrigerant is sucked into the suction space B of the compression chamber 30a subsequently through the accumulator 14, the suction pipe 16 and then through the suction hole 30d which are connected therewith.
Supposing that the suction hole 30d is a reference point, i.e., a zero degree (0.degree.), the refrigerant is compressed into the high temperature and high pressure refrigerant when the roller 26 orbits from a two hundred and twelve degree point to a two hundred and twenty degree point (212.degree.-220.degree.). Then, when the roller further orbits to a three hundred and thirty degree point (330.degree.), the discharge valve 40 disposed at the upper flange 36 is open so as to permit the refrigerant to be discharged through the discharge port 36a. The maximum compression noise generated during rotation of the roller 26 from the two hundred and twenty degree point to the three hundred and thirty degree point (220.degree.-330.degree.) is reduced by the resonance chamber 30c of the cylinder 30 which is so formed at the resonance chamber 30c as to communicate with the compression space A.
In the conventional hermetic rotary compressor, the structure for reducing the noise generated during the refrigerant compressing operation, i.e., the resonance chamber 30c is formed in the inner peripheral surface of the cylinder 30 so as to communicate with the compression space A. This means that the compressed refrigerant is not completely discharged through the discharge port; rather, some of the refrigerant is introduced into the resonance chamber which functions as a `Dead volume`. Accordingly, the discharge pressure becomes lower, and the compressor performance is reduced.